A locking/unlocking device such as a safe or a coin-operated locker is known. In order to lock and unlock such a device, use of a key (physical key) or a password provided for the device can be considered.
When such a key or a password is lost or forgotten, there is a problem in that the device cannot be locked or unlocked. Use of an IC card (for example, a FeliCa (registered trademark) card) instead of such a key or password can also be considered. However, when the IC card is lost, there is a problem in that an IC card having the same card number cannot be reissued (a newly issued IC card has a different number). There is also a risk of duplication of the card number depending on the method in which it is implemented. Therefore, although it is possible to increase a security level of information held in the IC card itself, but the IC card is not necessarily suitable as a key used for locking and unlocking in consideration of the above-mentioned risk and problem when the IC card is lost or the like.
Therefore, a system for notifying of locking and unlocking on the basis of a telephone number of a caller is considered. For example, an authentication system that unlocks a door connected to an authentication device when a caller's number is transmitted from a mobile phone to the authentication device and the caller's number is coincident with a terminal number registered in the authentication device is known (see Patent Literature 1).